Glucose Ketone Index (GKI) Calculator
Calculate your glucose ketone index (GKI) from blood glucose (mmol/L or mg/dL) and blood ketones (BHB, mmol/L), and see which ketosis range the ratio falls in.
How it works
GKI = blood glucose (mmol/L) ÷ blood ketones (mmol/L) · glucose mmol/L = mg/dL ÷ 18
The glucose ketone index was proposed by Meidenbauer, Mukherjee and Seyfried (2015) as a single number that tracks metabolic state on ketogenic diets and in therapeutic fasting: blood glucose divided by blood beta-hydroxybutyrate, both in mmol/L. Lower values mean more ketosis relative to glucose. Values above 9 usually mean no meaningful ketosis, 3–6 is a common target on a ketogenic diet, and values near or below 1 are reached mainly in prolonged fasting or supervised therapeutic diets.
Worked example
Blood glucose 4.5 mmol/L (81 mg/dL) and blood ketones 1.2 mmol/L: GKI = 4.5 ÷ 1.2 = 3.75, which falls in the moderate ketosis range (3–6). The ketone level is within the nutritional ketosis range of 0.5–3.0 mmol/L.
Sources: Meidenbauer JJ, Mukherjee P, Seyfried TN (2015) The glucose ketone index calculator: a simple tool to monitor therapeutic efficacy for metabolic management of brain cancer. Nutr Metab 12:12 · Patient.info — Glucose ketone index calculator
Frequently asked questions
What is a good GKI?
It depends on the goal. For general ketogenic dieting, 3–6 is a common target; 6–9 reflects light ketosis, and values of 1–3 are aimed for mainly in supervised therapeutic protocols. There is no single “best” GKI for healthy people.
Can I use mg/dL glucose?
Yes — choose mg/dL and the calculator divides by 18 to get mmol/L. Ketone meters already report beta-hydroxybutyrate in mmol/L, so enter that value as it is.
Can I use urine or breath ketones?
No. The index was defined with blood beta-hydroxybutyrate. Urine strips measure acetoacetate and become unreliable once you adapt, and breath acetone uses different units.
When should I measure?
Take both readings at the same time, ideally 2–3 hours after a meal or in the morning before eating, and compare readings taken at the same time of day.
Is a very low GKI dangerous?
A low GKI from normal glucose and moderately high ketones is expected in fasting. But high ketones with high glucose — especially in people with type 1 diabetes — can signal ketoacidosis, which is an emergency. People on SGLT2 inhibitors or insulin should only pursue ketosis with medical supervision.
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This calculator gives general nutrition estimates for healthy adults and is not medical advice. People with diabetes, kidney disease, pregnancy or other conditions — and anyone using medication that affects blood sugar — should follow their doctor or dietitian.